Hello Surya,
- Existing Assignments option within Access Request shows the data from GRC Object Repository. It will show the latest SYNCed information only.
- In case the results are not correct, try running a fresh "Repository Object Sync" job from SPRO => IMG => Governance, Risk and Compliance =>Access Control =>Synchronization Jobs.
- You may run Incremental or Full Sync as needed.
Regards,
Rakesh Ram M
P.S : Check this SAP Note 2172233 - Existing Assignment not displaying roles